I upgraded to WordPress 3.1.2 and everytime I post something I get this:
One or more of your last posts has failed to send it's status update to Twitter. Your Tweet has been saved in your post custom fields, and you can re-Tweet it at your leisure.
Code 0: Twitter did not return a recognized response code.
Sorry! I couldn't get in touch with the Twitter servers to post your new blog post. Your tweet has been stored in a custom field attached to the post, so you can Tweet it manually if you wish!
However, I don't have any issues with WordPress 3.1.1!